Players can only accumulate pitching statistics or hitting statistics in a given Game Week, not both.
For example, Shohei Ohtani is capable of both pitching and hitting. Sorare MLB players will need to decide whether to count Ohtani's pitching OR hitting statistics during a given Game Week. This means he can only be played specifically as a Starting Pitcher (for pitching statistics), Corner Infielder, or Extra Hitter (for hitting statistics).
As a result, Shohei Ohtani cannot be selected for the Flex position.